The present invention relates to portable bedding, specifically to a sleeping bag allowing the user to adjust the bag between a conventional rectangular bag and a tapered mummy-style bag, thereby adjusting the internal volume of the bag.
Sleeping bags can be uncomfortable, and when they are uncomfortable, they can deny their users much-needed rest. Sleeping bag comfort is largely a matter of warmthxe2x80x94that is, providing the occupant with the correct amount of insulation to suit the existing conditions. Sleeping bag comfort is also a matter of providing the user with adequate freedom of movement. These two aspects of sleeping bag comfort can work against each other. For example, for similarly shaped bags, the more room there is inside a bag, the more freedom of movement is available to the occupant. However, the more room inside a bag, the more air space the user""s body is required to heat and the more outer bag surface is exposed to the cold. Most sleeping bags provide comfort in only a rather narrow range of temperatures. Accordingly, sleeping bag manufacturers have long sought means of effectively adjusting the suitability of sleeping bags to fit a wider range of temperatures.
Accordingly, it is desired to provide a sleeping bag having increased warmth during cooler weather and increased freedom of movement during warmer weather, and to provide a more user-friendly, yet economical sleeping bag.
The present invention provides a sleeping bag that allows the user to adjust the sleeping bag between a conventional rectangular bag and a narrowed mummy-style bag, thereby adjusting the internal volume of the bag. The adjustable feature allows a user to reduce the inner air space of the bag to form a tapered mummy-style shape for maximum comfort in cold weather. The sleeping bag user also may expand the inner space of the bag into a non-tapered rectangular shape for maximum comfort and freedom of movement in warm weather. This adjustment may be accomplished quickly and easily via one or more secondary external zippers or other adjusting mechanisms, thereby allowing the sleeping bag user to respond to even sudden changes in temperature.